This invention is generally directed to photoconductive imaging members, and more specifically to imaging members with polyphosphazene binders. The present invention in one embodiment is directed to layered imaging members comprised of charge transport layers with charge transport molecules dispersed in polyphosphazene binders. In a specific embodiment, the present invention relates to layered imaging members comprised of a photogenerating layer and a hole transport layer wherein the transport molecules thereof are dispersed in a polyphosphazene resinous binder. Further, in another embodiment of the present invention the imaging member is comprised of a supporting substrate, a photogenerating layer, and in contact therewith a charge, especially a hole transport layer comprised of hole transport molecules dispersed in a polyphosphazene resinous binder. The charge transport layer can be located as the top layer of the imaging member, or alternatively it may be situated between a supporting substrate and the photogenerating layer. The aforementioned polyphosphazene binders possess a number of advantages including, for example, the solubility thereof in a number of solvents such as aromatic solvents including toluene, tetrahydrofuran, xylene, and benzene, and aliphatic solvents such as halogenated hydrocarbons thus permitting, for example, improved coatability thereof with organic charge transport components utilizing various known processes such as spray, dip, and draw-down coating. Another advantage associated with many of the imaging members of the present invention resides in the ability to modify the substituents, or side groups present on the polyphosphazenes thereby providing, for example, substantial latitude in improving the mechanical and surface properties of the charge transport layers including, for example, environmental stability, abrasion resistence, elimination of a protective top coating, and/or excellent paper stripping characteristics for the imaging member. The imaging members of the present invention can be selected for a number of imaging and printing processes including electrophotographic imaging and printing processes for an extended number of imaging cycles, while substantially avoiding, or minimizing undesirable charge transport molecule crystallization. Also, the imaging members of the present invention can be selected for a number of color imaging and printing processes.
The formation and development of electrostatic latent images on the imaging surfaces of photoconductive materials by electrostatic means is well known. Numerous different photoconductive members for use in xerography are known such as selenium, alloys of selenium, layered imaging members comprised of aryl amine charge transport layers, reference U.S. Pat. No. 4,265,990, and imaging members with charge transport layers comprised of polysilylenes, reference U.S. Pat. No. 4,618,551. The disclosures of the aforementioned patents are totally incorporated herein by reference. With the aforementioned imaging members, especially those of the '990 patent, there are selected aryl amine charge transport layers, which aryl amines are soluble in halogenated hydrocarbons such as methylene chloride, and these hydrocarbons can be toxic, especially without fabrication precautions. The aforementioned disadvantage is avoided with the imaging members of the present invention in that the polyphosphazene selected as the charge transport resin binder is soluble in nontoxic solvents as illustrated herein, such as toluene, tetrahydrofuran and xylene. Further, the polyphosphazenes of the present invention can also be selected as resinous binders for imaging members with electron transport layers, reference U.S. Pat. No. 4,474,865, the disclosure of which is totally incorporated herein by reference.
In U.S. Pat. No. 4,869,988 and U.S. Pat. No. 4,946,754 entitled, respectively, PHOTOCONDUCTIVE IMAGING MEMBERS WITH N,N-BIS(BIARYLYL)ANILINE, OR TRIS(BIARYLYL)AMINE CHARGE TRANSPORTING COMPONENTS, and PHOTOCONDUCTIVE IMAGING MEMBERS WITH BIARYLYL DIARYLAMINE CHARGE TRANSPORTING COMPONENTS, the disclosures of which are totally incorporated herein by reference, there are described layered photoconductive imaging members with transport layers incorporating biarylyl diarylamines, N,N-bis(biarylyl)anilines, and tris(biarylyl)amines as charge transport compounds. In the above-mentioned patents, there are disclosed improved layered photoconductive imaging members comprised of a supporting substrate, a photogenerating layer optionally dispersed in an inactive resinous binder, and in contact therewith a charge transport layer comprised of the above-mentioned charge transport compounds, or mixtures thereof dispersed in resinous binders.
Examples of specific hole transporting components disclosed in U.S. Pat. No. 4,869,988 include N,N-bis(4-biphenylyl)-3,5-dimethoxyaniline (Ia); N,N-bis(4-biphenylyl)-3,5-dimethylaniline (Ib); N,N-bis(4-methyl-4'-biphenylyl)-3-methoxyaniline (Ic); N,N-bis(4-methyl-4'-biphenylyl)-3-chloroaniline (Id); N,N-bis(4-methyl-4'-biphenylyl)-4-ethylaniline (Ie); N,N-bis(4-chloro-4'-biphenylyl)-3-methylaniline (If); N,N-bis(4-bromo-4'-biphenylyl)-3,5-dimethoxy aniline (Ig); 4-biphenylyl bis(4-ethoxycarbonyl-4'-biphenylyl)amine (IIa); 4-biphenylyl bis(4-acetoxymethyl-4'-biphenylyl)amine (IIb); 3-biphenylyl bis(4-methyl-4'-biphenylyl)amine (IIc); 4-ethoxycarbonyl-4'-biphenylyl bis(4-methyl-4'-biphenylyl)amine (IId); and the like.
Examples of specific hole transporting compounds disclosed in U.S. Pat. No. 4,946,754 include bis(p-tolyl)-4-biphenylylamine (IIa); bis(p-chlorophenyl)-4-biphenylylamine (IIb); N-phenyl-N-(4-biphenylyl)-p-toluidine (IIc); N-(4-biphenylyl)-N-(p-chlorophenyl)-p-toluidine (IId); N-phenyl-N-(4-biphenylyl)-p-anisidine (IIe); bis(m-anisyl)-4-biphenylylamine (IIIa); bis(m-tolyl)-4-biphenylylamine (IIIb); bis(m-chlorophenyl)-4-biphenylylamine (IIIc); N-phenyl-N-(4-biphenylyl)-m-toluidine (IIId); N-phenyl-N-(4-bromo-4'-biphenylyl)-m-toluidine (IVa); diphenyl-4-methyl-4'-biphenylylamine (IVb); N-phenyl-N-(4-ethoxycarbonyl-4'-biphenylyl)-m-toluidine (IVc); N-phenyl-N-(4-methoxy-4'-biphenylyl)-m-toluidine (IVd); N-(m-anisyl)-N-(4-biphenylyl)-p-toluidine (IVe); bis(m-anisyl)-3-biphenylylamine (Va); N-phenyl-N-(4-methyl-3'-biphenylyl)-p-toluidine (Vb); N-phenyl-N-(4-methyl-3'-biphenylyl)-m-anisidine (Vc); bis(m-anisyl)-3-biphenylylamine (Vd); bis(p-tolyl)-4-methyl-3'-biphenylylamine (Ve); N-p-tolyl-N-(4-methoxy-3'-biphenylyl)-m-chloroaniline (Vf), and the like.
It is also indicated in the aforementioned two copending applications that there may be selected as resin binders for the charge transport molecules those components as illustrated in U.S. Pat. No. 3,121,006 including polycarbonates, polyesters, epoxy resins, polyvinylcarbazole; and also wherein for the preparation of the charge transport layer with a polycarbonate there is selected methylene chloride as a solvent.
In a patentability search report there were recited the following U.S. Pat. No. 4,657,993, the disclosure of which is totally incorporated herein by reference, directed to polyphosphazene homopolymers and copolymers of the formula as recited, for example, in the Abstract of the Disclosure, which components may be selected as photoconductive materials and for other uses, see column 1, and continuing on to column 2; and as background interest U.S. Pat. No. 3,370,020 directed to processes for the preparation of phosphonitrilic polymer mixtures, reference the Abstract of the Disclosure, U.S. Pat. No. 3,515,688 related to phosphonitrile elastomers, reference for example the Abstract of the Disclosure; U.S. Pat. No. 3,702,833 directed to curable fluorophosphazene polymers, see for example column 1; and U.S. Pat. No. 3,856,712 directed to polyphosphazene copolymers which are elastomers. The disclosures of each of the aforementioned patents are totally incorporated herein by reference. The polyphosphazenes of the '993 patent and other polyphosphazenes illustrated hereinafter are particularly useful as resinous binders for the invention of the present application.
While imaging members with various charge transporting substances, especially hole transports, including the aryl amines disclosed in the prior art, are suitable for their intended purposes, there continues to be a need for improved imaging members, particularly layered members, with resin binders that are soluble in a number of solvents. Another need resides in the provision of layered imaging members that are compatible with liquid developer compositions. Further, there continues to be a need for layered imaging members wherein the layers are sufficiently adhered to one another to allow the continuous use of such members in repetitive imaging systems. Also, there continues to be a need for improved layered imaging members comprised of hole transport layers wherein the problems of transport molecule crystallization, bleeding and leaching are avoided or minimized. Furthermore, there is a need for imaging members with charge transport compounds or polymers dispersed in polyphosphazene resin binders that are soluble in nontoxic solvents, and wherein the resulting image members are inert to the users thereof. A further need resides in the provision of photoconductive imaging members with desirable mechanical characteristics.